National Weather Service Text Product
AFOS product SRGPUB
Dates interpreted at 00:00 UTCDisplaying AFOS PIL: SRGPUB
Product Timestamp: 2025-09-04 12:14 UTC
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420
UXUS97 KPUB 041214
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0613 MDT Thursday, September 4, 2025
This forecast is for Villa Grove, CO for Thursday, September 4, 2025:
If the trigger temperature of 66.4 F/19.1 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1185 ft/min (6.0 m/s)
Maximum height of thermals.................. 23035 ft MSL (14069 ft AGL)
Forecast maximum temperature................... 80.0 F/27.1 C
Time of trigger temperature.................... 1000 MDT
Time of overdevelopment........................ 1500 MDT
Middle/high clouds during soaring window....... Broken/overcast thin middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 20296 ft MSL (11330 ft AGL)
Thermal soaring outlook for Friday 09/05....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:36:20 / 19:28:33 MDT
Total possible sunshine........... 12 hr 52 min 14 sec (772 min 14 sec)
Altitude of sun at 13:02:27 MDT... 58.60 degrees
Upper air data from numerical model forecast valid on 09/04/2025 at 0600 MDT
Freezing level.................. 15545 ft MSL (6579 ft AGL)
Convective condensation level... 20402 ft MSL (11436 ft AGL)
Lifted condensation level....... 21798 ft MSL (12832 ft AGL)
Lifted index.................... -1.9
K index......................... +14.2
Height Temperature Wind Wind Spd Lapse Rate ConvectionT Thermal Lift Rate
ft MSL deg C deg F Dir kt m/s C/km F/kft deg C deg F Index fpm m/s
--------------------------------------------------------------------------------
50000 -64.4 -83.9 285 33 17 1.9 1.0 M M M M M
45000 -61.3 -78.3 280 38 19 2.9 1.6 M M M M M
40000 -56.1 -69.0 285 22 12 7.5 4.1 M M M M M
38000 -51.5 -60.7 290 23 12 7.7 4.2 M M M M M
36000 -46.9 -52.4 295 23 12 7.7 4.2 M M M M M
34000 -42.0 -43.6 295 23 12 8.2 4.5 M M M M M
32000 -37.1 -34.8 290 22 11 8.1 4.5 M M M M M
30000 -32.3 -26.1 285 19 10 7.8 4.3 32.1 89.7 4.2 M M
29000 -30.0 -22.0 280 17 9 7.8 4.3 31.4 88.5 3.8 M M
28000 -27.6 -17.7 275 15 8 7.8 4.3 30.8 87.5 3.3 M M
27000 -24.8 -12.6 275 13 7 7.6 4.1 29.7 85.4 2.5 M M
26000 -22.5 -8.5 275 11 6 7.6 4.1 28.9 84.0 1.8 M M
25000 -20.3 -4.5 275 10 5 7.6 4.2 28.2 82.8 1.3 M M
24000 -18.0 -0.4 280 9 5 7.6 4.2 27.4 81.3 0.6 M M
23000 -15.7 3.7 290 8 4 7.6 4.2 26.6 80.0 -0.0 1377 7.0
22000 -13.4 7.9 300 8 4 6.9 3.8 26.0 78.8 -0.6 1279 6.5
21000 -11.8 10.8 300 10 5 5.4 3.0 24.5 76.1 -2.0 1201 6.1
20000 -10.3 13.5 300 13 7 5.6 3.1 23.1 73.5 -3.4 1125 5.7
19500 -9.5 14.9 295 14 7 5.6 3.0 22.4 72.3 -4.1 1087 5.5
19000 -8.6 16.5 295 15 8 6.8 3.7 21.8 71.3 -4.7 1046 5.3
18500 -7.7 18.1 300 16 8 6.8 3.7 21.3 70.3 -5.2 1003 5.1
18000 -6.7 19.9 300 16 8 7.6 4.2 20.8 69.5 -5.7 959 4.9
17500 -5.4 22.3 305 17 9 8.8 4.8 20.6 69.1 -5.9 906 4.6
17000 -4.1 24.6 310 18 9 8.8 4.8 20.5 68.9 -6.2 853 4.3
16500 -2.8 27.0 310 18 9 9.1 5.0 20.3 68.6 -6.3 799 4.1
16000 -1.5 29.3 315 18 9 9.1 5.0 20.2 68.4 -6.5 744 3.8
15500 -0.1 31.8 320 18 9 9.4 5.2 20.2 68.3 -6.6 689 3.5
15000 1.3 34.3 320 18 10 9.5 5.2 20.1 68.2 -6.7 631 3.2
14500 2.7 36.9 325 19 10 8.4 4.6 20.1 68.2 -6.7 574 2.9
14000 4.0 39.2 325 19 10 9.7 5.3 19.9 67.8 -6.9 520 2.6
13500 6.1 43.0 330 19 10 8.6 4.7 19.8 67.7 -7.1 436 2.2
13000 7.4 45.3 330 19 10 9.8 5.4 19.7 67.4 -7.2 380 1.9
12500 8.9 48.0 330 19 10 9.3 5.1 19.7 67.4 -7.3 323 1.6
12000 10.2 50.4 325 19 10 9.5 5.2 19.6 67.2 -7.5 268 1.4
11750 10.9 51.6 325 19 10 10.6 5.8 19.6 67.3 -7.5 239 1.2
11500 11.7 53.1 325 19 10 9.2 5.0 19.6 67.3 -7.5 209 1.1
11250 12.3 54.1 325 18 9 7.6 4.2 19.5 67.1 -7.6 183 0.9
11000 12.8 55.0 325 18 9 7.1 3.9 19.3 66.8 -7.8 160 0.8
10750 13.4 56.1 325 18 9 9.2 5.1 19.2 66.5 -8.0 135 0.7
10500 14.0 57.2 320 18 9 5.9 3.2 19.1 66.4 -8.1 109 0.6
10250 14.1 57.4 320 17 9 -0.8 -0.5 18.5 65.3 -8.8 98 0.5
10000 14.0 57.2 315 16 8 -3.1 -1.7 17.6 63.7 -9.7 96 0.5
9750 13.8 56.8 305 15 8 2.2 1.2 16.7 62.1 -10.6 93 0.5
9500 13.9 57.0 300 14 7 -8.2 -4.5 16.1 61.0 -11.3 84 0.4
9250 11.9 53.4 290 10 5 -44.7 -24.5 13.4 56.1 -14.0 137 0.7
9000 8.9 48.0 255 6 3 -8.9 -4.9 9.7 49.5 -17.8 220 1.1
8750 M M M M M M M M M M M M
8500 M M M M M M M M M M M M
8250 M M M M M M M M M M M M
8000 M M M M M M M M M M M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
09/04/2025 at 0900 MDT | 09/04/2025 at 1200 MDT
|
CAPE... 0.0 LI... +0.7 | CAPE... +72.5 LI... -0.9
CINH... 0.0 K Index... +8.8 | CINH... -0.0 K Index... +16.6
|
Height Temperature Wnd WndSpd Lapse Rate | Temperature Wnd WndSpd Lapse Rate
ft MSL deg C deg F Dir kt m/s C/km F/kft | deg C deg F Dir kt m/s C/km F/kft
--------------------------------------------------------------------------------
50000 -65.5 -85.9 285 31 16 2.1 1.1 | -65.5 -85.9 275 34 18 1.3 0.7
45000 -61.8 -79.2 275 36 19 3.5 1.9 | -62.4 -80.3 265 40 21 4.1 2.2
40000 -56.1 -69.0 280 25 13 7.5 4.1 | -56.0 -68.8 265 31 16 7.1 3.9
38000 -51.8 -61.2 280 23 12 7.3 4.0 | -51.8 -61.2 270 30 15 6.9 3.8
36000 -47.4 -53.3 275 22 11 7.3 4.0 | -47.7 -53.9 275 28 15 6.9 3.8
34000 -42.3 -44.1 275 22 11 8.6 4.7 | -42.6 -44.7 275 28 15 8.8 4.8
32000 -36.5 -33.7 275 22 11 8.6 4.7 | -36.7 -34.1 280 29 15 8.8 4.8
30000 -31.6 -24.9 275 21 11 8.0 4.4 | -32.0 -25.6 275 25 13 7.7 4.2
29000 -29.2 -20.6 275 20 10 8.0 4.4 | -29.7 -21.5 275 22 12 7.7 4.2
28000 -26.9 -16.4 275 20 10 7.5 4.1 | -27.4 -17.3 275 20 10 7.4 4.0
27000 -24.6 -12.3 275 18 9 7.3 4.0 | -25.2 -13.4 275 19 10 7.2 3.9
26000 -22.4 -8.3 270 17 9 7.3 4.0 | -23.0 -9.4 275 17 9 7.2 4.0
25000 -20.2 -4.4 270 15 8 7.3 4.0 | -20.9 -5.6 275 16 8 7.2 4.0
24000 -18.0 -0.4 270 13 7 7.4 4.1 | -18.8 -1.8 275 14 7 6.9 3.8
23000 -15.8 3.6 270 12 6 7.4 4.1 | -16.7 1.9 275 13 7 6.9 3.8
22000 -13.5 7.7 275 10 5 7.1 3.9 | -14.7 5.5 275 11 6 6.8 3.7
21000 -11.8 10.8 280 10 5 5.7 3.1 | -12.9 8.8 275 12 6 6.1 3.4
20000 -10.2 13.6 285 11 6 5.8 3.2 | -11.1 12.0 275 13 7 6.2 3.4
19500 -9.4 15.1 285 11 6 5.8 3.2 | -10.2 13.6 275 13 7 6.1 3.3
19000 -8.5 16.7 290 12 6 6.8 3.7 | -9.2 15.4 280 13 7 7.5 4.1
18500 -7.5 18.5 295 12 6 6.8 3.7 | -8.1 17.4 280 13 7 7.6 4.2
18000 -6.5 20.3 295 13 7 7.2 3.9 | -7.0 19.4 285 13 7 8.1 4.4
17500 -5.3 22.5 300 13 7 7.9 4.3 | -5.7 21.7 290 12 6 9.2 5.0
17000 -4.2 24.4 305 14 7 7.8 4.3 | -4.4 24.1 295 10 5 9.2 5.1
16500 -3.0 26.6 310 14 7 8.6 4.7 | -3.1 26.4 305 9 5 9.5 5.2
16000 -1.7 28.9 315 14 7 8.6 4.7 | -1.7 28.9 305 9 5 9.5 5.2
15500 0.2 32.4 325 14 7 9.1 5.0 | 0.4 32.7 305 9 5 9.7 5.3
15000 1.6 34.9 330 14 7 9.2 5.0 | 1.8 35.2 305 9 5 9.7 5.3
14500 2.9 37.2 330 15 8 9.0 4.9 | 3.3 37.9 305 9 5 9.5 5.2
14000 4.3 39.7 330 15 8 9.7 5.3 | 4.7 40.5 310 9 5 9.9 5.4
13500 5.8 42.4 330 15 8 8.9 4.9 | 6.2 43.2 310 9 5 8.0 4.4
13000 7.1 44.8 330 16 8 9.6 5.3 | 7.6 45.7 310 9 5 11.1 6.1
12500 8.5 47.3 330 16 8 9.3 5.1 | 9.2 48.6 310 9 4 9.9 5.5
12000 9.8 49.6 325 17 9 9.3 5.1 | 10.5 50.9 310 8 4 9.9 5.4
11750 10.5 50.9 325 17 9 9.7 5.3 | 11.3 52.3 310 8 4 11.0 6.0
11500 11.2 52.2 325 17 9 9.1 5.0 | 12.1 53.8 310 8 4 10.5 5.7
11250 11.8 53.2 320 17 9 8.3 4.6 | 12.9 55.2 310 8 4 10.1 5.5
11000 12.4 54.3 320 17 9 8.0 4.4 | 13.6 56.5 310 8 4 10.0 5.5
10750 13.0 55.4 320 17 9 9.1 5.0 | 14.4 57.9 310 8 4 10.2 5.6
10500 13.7 56.7 315 17 9 7.1 3.9 | 15.2 59.4 310 8 4 10.4 5.7
10250 13.9 57.0 310 16 8 2.6 1.5 | 15.9 60.6 310 8 4 10.4 5.7
10000 14.1 57.4 305 15 8 2.6 1.4 | 16.7 62.1 310 8 4 10.8 5.9
9750 14.2 57.6 300 14 7 1.0 0.6 | 17.5 63.5 310 7 4 9.5 5.2
9500 14.2 57.6 295 13 7 3.5 1.9 | 18.3 64.9 315 7 4 14.2 7.8
9250 14.8 58.6 285 10 5 14.2 7.8 | 19.8 67.6 310 7 4 28.5 15.6
9000 15.7 60.3 265 7 4 3.0 1.7 | 21.9 71.4 310 6 3 19.6 10.7
8750 M M M M M M M | M M M M M M M
8500 M M M M M M M | M M M M M M M
8250 M M M M M M M | M M M M M M M
8000 M M M M M M M | M M M M M M M
09/04/2025 at 1500 MDT | 09/04/2025 at 1800 MDT
|
CAPE... +131.9 LI... -0.6 | CAPE... +163.0 LI... -1.1
CINH... -9.6 K Index... +26.1 | CINH... -48.2 K Index... +25.4
|
Height Temperature Wnd WndSpd Lapse Rate | Temperature Wnd WndSpd Lapse Rate
ft MSL deg C deg F Dir kt m/s C/km F/kft | deg C deg F Dir kt m/s C/km F/kft
--------------------------------------------------------------------------------
50000 -64.7 -84.5 275 38 19 1.1 0.6 | -63.7 -82.7 275 38 20 1.1 0.6
45000 -62.0 -79.6 265 47 24 4.1 2.2 | -61.6 -78.9 265 48 25 2.3 1.3
40000 -55.6 -68.1 260 41 21 6.8 3.7 | -57.6 -71.7 260 43 22 8.6 4.7
38000 -51.6 -60.9 260 36 19 6.6 3.6 | -52.8 -63.0 260 36 19 8.0 4.4
36000 -47.7 -53.9 265 32 16 6.6 3.6 | -48.0 -54.4 260 29 15 8.0 4.4
34000 -42.5 -44.5 265 30 15 9.3 5.1 | -41.9 -43.4 265 25 13 9.3 5.1
32000 -36.2 -33.2 265 29 15 9.3 5.1 | -36.3 -33.3 270 23 12 9.2 5.0
30000 -31.7 -25.1 265 25 13 7.1 3.9 | -31.4 -24.5 270 19 10 8.0 4.4
29000 -29.6 -21.3 270 23 12 7.1 3.9 | -29.0 -20.2 270 17 9 8.0 4.4
28000 -27.5 -17.5 270 21 11 7.0 3.9 | -26.6 -15.9 270 15 8 7.6 4.2
27000 -25.3 -13.5 270 19 10 7.0 3.8 | -24.6 -12.3 270 13 7 7.0 3.9
26000 -23.2 -9.8 275 18 9 7.0 3.8 | -22.5 -8.5 275 11 5 7.0 3.9
25000 -21.1 -6.0 275 16 8 7.1 3.9 | -20.4 -4.7 280 8 4 7.0 3.9
24000 -19.3 -2.7 275 16 8 6.0 3.3 | -18.3 -0.9 285 7 4 7.2 4.0
23000 -17.5 0.5 280 15 8 6.1 3.4 | -16.1 3.0 285 7 4 7.3 4.0
22000 -15.7 3.7 280 14 7 6.5 3.6 | -14.0 6.8 290 6 3 7.4 4.0
21000 -13.3 8.1 285 14 7 8.8 4.9 | -12.1 10.2 290 7 4 6.4 3.5
20000 -10.8 12.6 285 13 7 8.9 4.9 | -10.2 13.6 285 8 4 6.4 3.5
19500 -9.5 14.9 290 12 6 9.1 5.0 | -9.3 15.3 280 8 4 6.4 3.5
19000 -8.3 17.1 290 12 6 7.7 4.2 | -8.4 16.9 280 8 4 6.6 3.6
18500 -7.1 19.2 290 11 6 7.6 4.2 | -7.4 18.7 280 9 5 6.6 3.6
18000 -6.0 21.2 285 10 5 8.1 4.4 | -6.5 20.3 280 9 5 6.6 3.6
17500 -4.6 23.7 285 9 5 9.8 5.4 | -5.0 23.0 280 11 5 7.0 3.8
17000 -3.2 26.2 285 9 5 9.8 5.4 | -3.9 25.0 280 11 6 7.1 3.9
16500 -1.7 28.9 285 9 4 9.8 5.4 | -2.8 27.0 280 12 6 8.1 4.4
16000 0.5 32.9 285 8 4 9.8 5.4 | -1.7 28.9 275 14 7 8.0 4.4
15500 2.0 35.6 280 8 4 10.0 5.5 | -0.5 31.1 275 15 7 8.1 4.4
15000 3.5 38.3 280 7 4 10.4 5.7 | 0.7 33.3 275 16 8 8.5 4.7
14500 4.8 40.6 280 7 4 8.1 4.4 | 1.7 35.1 270 16 8 6.6 3.6
14000 6.2 43.2 280 7 4 9.5 5.2 | 3.0 37.4 270 17 9 8.5 4.6
13500 7.7 45.9 280 7 3 9.1 5.0 | 4.2 39.6 270 17 9 8.3 4.5
13000 9.1 48.4 280 7 3 10.6 5.8 | 5.6 42.1 270 18 9 9.7 5.3
12500 10.7 51.3 280 6 3 9.9 5.4 | 7.0 44.6 270 18 9 9.4 5.1
12000 12.0 53.6 280 6 3 9.5 5.2 | 8.2 46.8 270 19 10 7.9 4.4
11750 12.8 55.0 280 6 3 10.9 6.0 | 8.8 47.8 270 19 10 8.7 4.8
11500 13.6 56.5 280 6 3 10.4 5.7 | 9.4 48.9 270 19 10 8.5 4.7
11250 14.3 57.7 280 6 3 10.0 5.5 | 10.0 50.0 265 18 10 7.9 4.3
11000 15.1 59.2 280 6 3 9.6 5.3 | 10.6 51.1 265 19 10 7.5 4.1
10750 15.8 60.4 280 5 3 10.3 5.6 | 11.1 52.0 265 19 10 7.1 3.9
10500 16.6 61.9 280 5 3 10.6 5.8 | 11.6 52.9 265 19 10 6.7 3.6
10250 17.4 63.3 280 5 3 10.2 5.6 | 12.1 53.8 265 18 9 7.8 4.3
10000 18.1 64.6 280 5 3 10.1 5.6 | 12.7 54.9 265 18 9 8.6 4.7
9750 18.9 66.0 280 5 2 10.0 5.5 | 13.3 55.9 265 17 9 8.4 4.6
9500 19.6 67.3 280 4 2 10.8 5.9 | 13.9 57.0 265 17 9 9.5 5.2
9250 20.6 69.1 280 4 2 15.5 8.5 | 14.8 58.6 265 15 8 12.8 7.0
9000 22.0 71.6 275 4 2 24.8 13.6 | M M M M M M M
8750 M M M M M M M | M M M M M M M
8500 M M M M M M M | M M M M M M M
8250 M M M M M M M | M M M M M M M
8000 M M M M M M M | M M M M M M M
________________________________________________________________________________
This product is issued twice per day, once by approximately 0630 MST/0730 MDT
(1330 UTC). It is not continuously monitored nor updated after its initial
issuance.
The information contained herein is based on rawinsonde observation and/or
numerical weather prediction model data taken near Villa Grove, Colorado at:
North Latitude: 38 deg 16 min 03 sec
West Longitude: 105 deg 53 min 37 sec
Elevation: 7986 feet (2434 meters)
and may not be representative of other areas along the Front Range of the
Colorado Rocky Mountains. Note that some elevations in numerical weather
prediction models differ from actual station elevations, which can lead to
data which appear to be below ground. Erroneous data such as these should
not be used.
The content and format of this report as well as the issuance times are subject
to change without prior notice. Comments and suggestions are welcome and should
be directed to one of the addresses or phone numbers shown at the bottom of this
page. To expedite a response to comments, be sure to mention your interest in
the soaring forecast.
DEFINITIONS:
CAPE (Convective Available Potential Energy) - An integrated measure of the
energy available for convective development, also known as the positive
area on a thermodynamic diagram. Units are Joules per kilogram. Larger
values are indicative of greater instability and the possibility of
stronger convective activity, including thunderstorms. Values around or
greater than 1000 suggest the possibility of severe weather should
convective activity develop.
CIN (Convective Inhibition) - An integrated measure of the amount of energy
needed to initiate convective activity, also known as the negative area on
a thermodynamic diagram. Units are Joules per kilogram. The more negative
this number, the more energy is required to initiate convection. This
inhibitive energy can be overcome through surface heating, cooling aloft,
lifting mechanisms (orographic, frontal, gravity waves, etc.)
Convective Condensation Level - The height to which an air parcel possessing the
average saturation mixing ratio in the lowest 4000 feet of the airmass,
if heated sufficiently from below, will rise dry adiabatically until it
just becomes saturated. It estimates the base of cumulus clouds that are
produced by surface heating only.
Convection Temperature (ConvectionT) - The surface temperature required to make
the airmass dry adiabatic up to the given level. It can be considered a
"trigger temperature" for that level.
Freezing Level - The height where the temperature is zero degrees Celsius.
Height of Stable Layer - The height (between 12,000 and 18,000 feet above
mean sea level) where the smallest lapse rate exists. The location and
existence of this feature is important in the generation of mountain
waves.
K Index - A measure of stability which combines the temperature difference
between approximately 5,000 and 18,000 feet above the surface, the amount
of moisture at approximately 5,000 feet above the surface, and a measure
of the dryness at approximately 10,000 feet above the surface. Larger
positive numbers indicate more instability and a greater likelihood of
thunderstorm development. One interpretation of K index values regarding
soaring in the western United States is given in WMO Technical Note 158
and is reproduced in the following table:
below -10 no or weak thermals
-10 to 5 dry thermals or 1/8 cumulus with moderate thermals
5 to 15 good soaring conditions
15 to 20 good soaring conditions with occasional showers
20 to 30 excellent soaring conditions, but increasing
probability of showers and thunderstorms
above 30 more than 60 percent probability of thunderstorms
Lapse Rate - The change with height of the temperature. Negative values indicate
inversions.
Lifted Condensation Level - The height to which an air parcel possessing the
average dew point in the lowest 4000 feet of the airmass and the forecast
maximum temperature must be lifted dry adiabatically to attain saturation.
Lifted Index (LI) - The difference between the environmental temperature at a
level approximately 18,000 feet above the surface and the temperature of
an air parcel lifted dry adiabatically from the surface to its lifted
condensation level and then pseudoadiabatically thereafter to this same
level. The parcel's initial temperature is the forecast maximum
temperature and its dew point is the average dew point in the lowest 4000
feet of the airmass. Negative values are indicative of instability with
positive values showing stable conditions.
Lift Rate - An experimental estimate of the strength of thermals. It is
computed the same way as the maximum rate of lift but uses the actual
level rather than the maximum height of thermals in the calculation.
Also, none of the empirical adjustments based on cloudiness and K-index
are applied to these calculations.
Maximum Height of Thermals - The height where the dry adiabat through the
forecast maximum temperature intersects the environmental temperature.
Maximum Rate of Lift - An estimate of the maximum strength of thermals. It
is computed from an empirical formula which combines the expected maximum
height of thermals with the difference in the environmental temperatures
between the maximum height of thermals and the temperature 4,000 feet
above the ground. After this computation, further empirical adjustments
are made based on the value of the K-index and the amount and opacity of
middle and high level cloudiness expected between the time of trigger
temperature and the time of overdevelopment.
Middle/High Clouds - The amount and opacity of middle (altostratus, altocumulus)
or high (cirrus, cirrostratus, cirrocumulus) clouds. Broken means that
between 60% and 90% of the sky is covered by the cloud, with overcast
conditions occurring when more than 90% of the sky is covered by the cloud.
Thin implies that the clouds are predominantly transparent, meaning that
some sunlight is reaching the ground, in contrast to opaque which suggests
that little sunlight is reaching the ground.
Potential Height of Wave - The minimum of the following two heights:
1. Level above the height of stable layer (or 14,000 feet if none exists)
where the wind direction changes by 30 degrees or more
2. Level above the height of stable layer (or 14,000 feet if none exists)
where the wind speed no longer increases with height
PVA/NVA - Positive vorticity advection (PVA)/negative vorticity advection (NVA)
on the 500 millibar isobaric surface (approximately 18,000 feet above mean
sea level). Weak PVA has been shown to assist in mountain wave soaring.
Soaring Window - The time between the time the trigger temperature is reached
and the time of overdevelopment.
Thermal Index - The difference between the environmental temperature and the
temperature at a particular level determined by following the dry adiabat
through the forecast maximum temperature up to that level. Negative values
are indicative of thermal lift.
Thermal Soaring Index - An adjective rating (for sailplanes) based on the
computed maximum rate of lift, and the wind speed and middle and high
cloud cover expected during the soaring window (the time of the trigger
temperature and the time of overdevelopment) according to the following:
Maximum rate of lift Adjective Rating
>= 800 fpm Excellent
>= 400 and < 800 fpm Good
>= 200 and < 400 fpm Fair
< 200 fpm Poor
Time of Overdevelopment - The time one or more of the following phenomena,
which essentially shut off thermal lift, is expected to occur:
1. formation of broken to overcast convective cloud cover
2. formation of scattered to numerous downbursts
3. initiation of widespread precipitation
Time of Trigger Temperature - The time the surface temperature is expected to
reach the trigger temperature.
Trigger Temperature - The surface temperature required to make the first 4000
feet of the atmosphere dry adiabatic.
Wave Soaring Index - An empirical, adjective rating (for sailplanes) which
attempts to combine a variety of phenomena important in mountain wave
soaring into a single index number. Objective points are assigned to
these phenomena: wind speed and direction at 14,000 ft MSL, the static
stability in the 12,000-18,000 ft MSL layer, the wind speed gradient above
the stable layer, jet stream location and frontal and upper trough
movements.
042613